Apparatus for use in measuring fluid levels

ABSTRACT

A device for use in measuring stratified fluid levels in a container is disclosed. The device has a microwave transceiver sensor head attached to a waveguide sensor rod which is enclosed by a gauge tube. The rod end tubes are comprised of sections which allow them to be assembled or disassembled in a close quarters environment. The tube has a plurality of circumferentially and longitudinally spaced slots providing for the equalization of stratified fluids within the tube. The rod is generally radially centered in the tube by the use of a plurality of spacers which reside in notches in the rod. The spacers are adapted to not penetrate the slots in the tube. The rod can be removed from the tube for cleaning without draining the tank. Additionally, once the rod is removed from the tube, a cleaner brush or scraper can be used to remove any barnacles or other debris from within the tube and the longitudinal slots in the tube.

RELATED APPLICATION

This Application is a divisional of U.S. patent application Ser. No.11/299,436 filed on Dec. 12, 2005, which is a continuation of U.S.patent application Ser. No. 10/733,825 filed on Dec. 11, 2003, now U.S.Pat. No. 6,988,404, each titled “APPARATUS FOR USE IN MEASURING FLUIDLEVELS,” and both of which are hereby incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to devices for use in measuring the levelof one or more liquids in a container in general, and more particularly,to the measurement of fluid levels in a tank such as a fuel tank of aship.

BACKGROUND OF THE INVENTION

The measuring of the level of a fluid in a tank is important for manyreasons. For example, it is important for an operator of a ship or othermachine to know the amount of fuel that remains in a fuel tank.Traditionally, mechanical measuring systems and methods such as the useof floats have been used to ascertain the level of a particular liquidin a tank. More recently, a microwave wave guide has been utilized todetermine the level of a fluid in a tank. It is also desirable tomeasure the levels of stratified liquid in a tank. For example, a shipmay, for ballast purposes, keep its fuel tanks nearly full at all timesby replacing diesel fuel that is burned with seawater.

However, the installation of a measuring device in a fuel tank of a shipcan be problematic. First, the location of a fuel tank aboard a ship maymake it difficult to utilize a traditional straight waveguide rod due tothe shape of the hull or other structural considerations such asbulkheads, etc. In addition, in a salt water environment, problems candevelop with regards to keeping a measuring device free from theaccumulation of seaborne items that can negatively affect the accuracyof the measurements.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an apparatus for themeasurement of a fluid or multiple stratified fluids within a tank. Itis also an object of the present invention to allow the device to beinstalled in a location where operating space may be limited, such as inthe bowels of a ship. It is also an object of the present invention toprovide an apparatus that can be cleaned without draining the tank.

SUMMARY OF THE INVENTION

The present invention provides for a microwave transceiver sensor headthat is attached to a waveguide sensor rod which extends longitudinallythrough a gauge tube. The tube and the rod both extend from the top tothe bottom of the fluid tank. They are also comprised of sections, whichallows them to be assembled or disassembled in a close quartersenvironment, such as a lower deck of a ship with minimal headroom.Additionally, the tube has a plurality of circumferentially andlongitudinally spaced slots allowing for the equalization of multiplefluids within the tube. The rod is generally radially centered insideand outside the tube by the use of a plurality of spacers, which areattached to notches in the rod. Sections of the tube and the rod canalso be curved, facilitating the placement of the measuring device in atank with a curved bottom, such as a fuel tank defined by a slanted orcurved hull of a ship. Finally, since the rod is installed in sections,it can be removed in sections and cleaned, without draining the tank.Likewise, once the rod is removed from the tube, a cleaner or brush canbe used to remove any debris from within the tube, and ensure that theslots in the tube remain open to promote the equalization of fluid.

The above and other objects and advantages of the present inventionshall be made apparent from the accompanying drawings and the briefdescriptions thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above and thedetailed description of the embodiments given below, serve to explainthe principles of the invention.

FIG. 1 is a schematic cross-sectional view of the apparatus according tothe principles of the present invention shown in use aboard a ship.

FIG. 2 is an enlarged cross-section of the device shown in FIG. 1.

FIG. 3 is a cross-sectional view taken of line 3-3 of FIG. 2.

FIG. 4 is an enlarged partial cross-sectional view of the device shownin FIG. 2.

FIG. 5 is a cross-sectional view of a portion of an alternativeembodiment of the device with a curved section.

FIG. 6 is a schematic view of the device shown in FIG. 1, as it is beingcleaned.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures and to FIG. 1 in particular, an apparatus 10for measuring the level of one or more fluids 12,14 located in acontainer or tank 16 is shown. Here, the tank 16 is located in a ship 18but the apparatus 10 could equally be used to measure fluids in othertanks, i.e., tanks used with off-shore oil drilling operations, refinerystacks (also commonly referred to as displacer columns), or airplanefuel tanks.

The measuring device 10 is configured to measure fluid levels from thetop of the fuel tank 20 which as shown, is located below the deck 22 ofthe ship 18 and also to the very bottom 24 of the fuel tank 16. In aship 18, this may necessitate passing the measuring device 10 throughvarious bulkheads 26 or other decks 28 which form compartments 30 in thebottom of the ship 18. Accordingly, various sleeves 32 are used toassure that the aperture created in the bulkhead 26 or deck 28 does notadversely affect the structural integrity of the vessel 18.

As is more clearly shown in FIG. 2, the device 10 has a sensor head 34which is located above the deck 22 to allow for human 36 operation andinteraction. A deck collar 38 is utilized to ensure that the fuel 14,fumes, and seawater 12 do not penetrate the deck 22.

The sensor head 34 is attached to a sensor rod 40 which extends from thesensor head 34 to the bottom 24 of the fuel tank 16. The sensor rod 40which functions as a waveguide is located within a gauge tube 42 whichalso extends to the bottom 24 of the fuel tank 16. The sensor head 34will typically house a microwave transceiver which utilizes low powertime domain reflectometry radar (LPTDRR) circuitry. Attached to thesensor head 34 is a head flange 44 which is adapted to be attached to acorresponding container flange 46, which is typically attached to thecontainer or tank 16 via the deck collar 38.

In the illustrated embodiment, a tamper-proof brace or restraint 48 isattached to the head flange 44 with a tamper-proof fastener 50. Atypical tamper-proof fastener that will be utilized will be a screw orbolt with a raised head that requires a special socket to unscrew. Thetamper-proof restraint 48 prevents the hexagonal section 52 of thesensor head 34 from being rotated until the restraint 48 is removed.This prevents tampering with the device 10 and also prevents theinadvertent or unauthorized access to the tank 16 by removing the sensorhead 34.

As is more clearly shown in FIG. 4, a lower portion 54 of the sensorhead is threaded which allows it to be screwed and secured by acorresponding threaded section 56 of the head flange 44. In addition,the head flange 44 is attached to the container flange 46 with aplurality of bolts 58 or other like fasteners. A seal or gasket (notshown) may be sandwiched between the head flange 44 and the containerflange 46.

The gauge tube 42 is comprised of a plurality of gauge tube sections 60,62, 64, 66. While the total length of the tube is determined by the sizeor depth of the tank, normally the head tube section 60 and theintermediate tube sections 62, 64 will be of generally equal length.Generally, the length of these sections will be determined, in part, onthe amount of headspace available on the deck above the fuel tank. Inother words, the tube sections will generally be sized to allow fortheir movement through the passages of a ship 18 and insertion into thefuel tank 16. The end tube section 66 is typically sized to allow thegauge tube 42 to extend to the bottom 24 of the tank 16.

The plurality of gauge tube sections 60, 62, 64, 66 have a couplingflange 67 at each end of the tube sections which connect together withthe plurality of fasteners 68. The head section of the gauge tube 60 isalso connected with a plurality of fasteners 68 to the head flange 44.Additionally, each gauge tube section has a slot 70 which generally runsthe longitudinal length of the tube section. The slots 70 may becircumferentially positioned at different locations around the gaugetube 42, to ensure the equalization of fluid within the tube 42. Hence,even with stratified liquids, the fluid levels within the gauge tube 42will be representative of the fluid levels in the tank 16 at large. Theslots 70 are also generally of a width to not only allow for thetransfer and equalization of fluids, but also of a sufficient width, forexample, approximately 5 mm ( 3/16 inch), to resist becoming prematurelyclogged or otherwise inhibited by seaborne crustaceans or the like.Preferably the gauge tube sections will be made out of 70/30 coppernickel metal.

Located within the gauge tube 42 is the waveguide sensor rod 40. Likethe tube 42, the waveguide rod 40 is comprised of a plurality of rodsections 72, 74, 76, 78. The upper or head rod section 72 is connectedto the sensor head 34 via a threaded connection 80. The other rodsections are likewise adapted to be screwed together with a threadsection 80. Typically, each rod section will not have a length greaterthan 122 cm (48 inches). While the outer surface 81 of the rod 40 isgenerally circular, the outer surface 82 of the rod 40 generallyadjacent to the thread section 80 is flat, or hexagonal, thusfacilitating the use of a tool such as a wrench (not shown) to screw therod sections together. In addition, the rod 40 has a plurality of radialnotches 84 spaced longitudinally along the rod 40. The notches 84 areadapted to receive and hold spacers 86. The notches 84 prevent thespacers 86 from longitudinally moving along the rod 40, such as couldoccur during installation or cleaning of the rod 40. The spacers 86, asshown in FIG. 3, are generally disposed radially to the center of therod 40 within the tube 42. As shown, the spacers 86 have a plurality ofradial extensions 88 which have a width 90 that is generally greaterthan the width of the slot 70. This allows the rod sections to beinserted into the tube 42, or removed from the tube 42, without thespacers 86 snagging or otherwise getting caught in the longitudinalslots 70. Generally, the spacers will be made out of plastic and the rodwill be made out of 70/30 copper nickel metal.

As shown in FIG. 5, the present invention can also contain a rod andtube sections 92, 94 respectively that are curved. The elbow rod section92 and any rod sections below it may be comprised of a flexible orbendable material or construction to allow for the removal of the rod 40without disassembling the tube 42. Curved sections of the rod or tubesare attached to one another respectively in the same manner as thestraight sections. The curved section allows the device 10 to negotiatevarious obstructions within a tank 16, as well as allow for the device10 to extend to the very bottom 24 of the tank 16. In a shipboardinstallation, there is often not a straight or direct path from thelocation where the sensor head 34 is desired to be placed to the bottom24 of the fuel tank 16. Hence, the use of a curved tube and waveguiderod provides the necessary flexibility to overcome such installationconstraints.

As conceptually illustrated in FIG. 6, one of the advantages of themeasuring device 10 is that it may be cleaned without requiring the tank16 to be drained. When the device 10 is to be cleaned, one removes thetamper restraint 48, unscrews the sensor head 34 from the head flange44, and removes the first or head rod section 72. As the waveguide rodsections are removed from the tube 42 and the tank 16, they aredisconnected from each other and any debris 96 that has accumulated onthe rod 40 is removed. In alternative embodiments, a built-in brush 96could be used to clean the rod 40 as it is removed from the tank 16. Inaddition, after all the rod sections are removed from the tube 42, acleaner, brush, or scraper may be inserted into the tube itself to cleanit. Alternatively, a brush or scraper 99 could be attached to the bottomend 98 of the end rod section 78 so that the tube 42 is cleaned as therod 40 is removed. Here, in addition to the bristles on a brush 99cleaning the inside surface 100 of the tube 42, the plurality of slots70 would also be brushed open to ensure the unimpeded flow of fluid fromthe tank 16 to the interior or inside section of the tube 42.

While the present invention has been illustrated by description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the claims to such detail.Additional advantages and modifications will readily appear to thoseskilled in the art. The invention in its broader aspect is, therefore,not limited to the specific details, representative system, apparatus,and method, and illustrative example shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicants' general inventive concept.

1. A method for installing an apparatus for use in measuring fluidlevels in a container comprising: connecting slotted gauge tube sectionshaving flanges together with a plurality of fasteners; insertingwaveguide sensor rod sections into the tube sections; connecting the rodsections together; and attaching a microwave transceiver sensor head toone of the sections of the rod.
 2. The method of claim 1 wherein thecontainer has an enclosed top, the method further comprising exposingthe head by positioning it above the enclosed top of the container andexternally from the container.
 3. The method of claim 1 furthercomprising supporting the rod sections with the head.
 4. The method ofclaim 1 wherein the container has a bottom, the method furthercomprising extending the rod sections towards the bottom of thecontainer and at least as deep as the lowest fluid level desired to bemeasured.
 5. The method of claim 1 wherein the rod sections aregenerally of equal width, the rod sections having an outer surface, themethod further comprising: positioning the outer surface of at least onerod section at a point where an upper fluid will contact a gas; andpositioning the outer surface of at least one rod section at a pointwhere various stratified fluids will contact each other.
 6. The methodof claim 1 wherein the outer surface of the rod sections have generallyflat portions, the connecting step comprising screwing the rod sectionstogether with a tool in operational contact with the generally flatportions of the outer surface of the rod sections.
 7. The method ofclaim 1 wherein the outer surface of the rod sections has a hexagonalportion, the connecting step comprising screwing the rod sectionstogether with a tool in operational contact with the hexagonal portionof the outer surface of the rod sections.
 8. The method of claim 1further comprising: bolting a head flange to a corresponding containerflange; and connecting the head into the head flange.
 9. The method ofclaim 8 wherein the container has an enclosed top, the method furthercomprising exposing the head by positioning it above the enclosed top ofthe container and externally from the container.
 10. The method of claim8 further comprising attaching a tamper-proof restraint to the headflange.
 11. The method of claim 10 wherein the container has an enclosedtop, the method further comprising exposing the head by positioning itabove the enclosed top of the container and externally from thecontainer.
 12. A method for installing an apparatus for use in measuringfluid levels in a container, the container having a bottom and anenclosed top, by determining the point where an upper fluid contacts agas or where various stratified fluids contact each other comprising:connecting slotted gauge tube sections having flanges together with aplurality of fasteners; inserting generally equal width waveguide sensorrod sections into the tube sections; connecting the rod sectionstogether; extending the rod sections towards the bottom of the containerand at least as deep as the lowest fluid level desired to be measured;positioning an outer surface of at least one rod section at a pointwhere the upper fluid will contact the gas; positioning the outersurface of at least one rod section at a point where the variousstratified fluids will contact each other; attaching a microwavetransceiver sensor head to one of the sections of the rod; supportingthe rod sections with the head; and exposing the head by positioning itabove the enclosed top of the container and externally from thecontainer.
 13. A method for cleaning an apparatus for use in measuringfluid levels in a container comprising: removing waveguide sensor rodsections from a gauge tube; disconnecting the rod sections; cleaning therod sections; inserting the rod sections into the tube; and connectingthe rod sections together.
 14. The method of claim 13 wherein the methodis performed without draining the container.
 15. The method of claim 14wherein the tube has a plurality of circumferentially and/orlongitudinally spaced slots therein.
 16. The method of claim 13 whereinat least one rod section has a brush attached thereto, the methodfurther comprising: cleaning the tube with the brush as the rod sectionsare removed from the tube.
 17. The method of claim 13 wherein at leastone rod section has a scraper attached thereto, the method furthercomprising: cleaning the tube with the scraper as the rod sections areremoved from the tube.
 18. The method of claim 13 further comprising:inserting a cleaner into the tube; and cleaning the tube with thecleaner.
 19. The method of claim 18 wherein the method is performedwithout draining the container.
 20. The method of claim 13 furthercomprising removing a microwave transceiver sensor head from a headflange.